1. Field of the Invention
The present invention relates to a rotary electric shaver in which an inner cutter rotates while sliding against a substantially disc-shaped outer cutter, thus cutting hair (whiskers, etc) advanced into slits formed in the outer cutter.
2. Description of the Related Art
Electric shavers of this type are commonly known in which the feel of the shave is enhanced by making the outer cutter capable of floating up and down (capable of sinking in). In such cases, if the outer cutter is made so that it not only moves in the up-and-down direction but also tilts in any direction, so as to tilt along the curvature of the shaving surface, the tightness of the outer cutter against the shaving surface is enhanced, and the feel of the shave is further enhanced.
Making the outer cutter floatable in the up-and-down direction and also tiltable in any direction is described in Japanese Patent Application National Publication (Kohyo) PCT (WO) H9-503424/1997 U.S. Pat. No. 5,625,950. Here, a skin supporting rim (outer cutter ring) that encloses the outer circumference of the outer cutter is provided, a protrusion that protrudes outward of the outer cutter is provided in that skin supporting rim, and that protrusion is made to engage, so that it can turn, in an engagement surface on the side of an outer cutter holder (outer cutter frame). In other words, the skin supporting rim (outer cutter ring) enclosing the outer cutter is made swivel (or pivotable) relative to both the outer cutter and the outer cutter holder. That skin supporting rim functions, when the outer cutter is forcefully pressed against the skin, to prevent the outer circumferential edge of the outer cutter from burying deeply into the skin so that the shave becomes excessive or the skin is harmed.
In the shavers of Japanese Patent Application National Publication (Kohyo) PCT (WO) H9-503424/1997 U.S. Pat. No. 5,625,950, the outer circumferential side of the skin supporting rim enclosing the outer circumference of the outer cutter is made to engage the outer cutter holder so that it can turn. In other words, the skin supporting rim turns about an axis that passes through the center of the outer cutter and is parallel to the upper surface of the outer cutter (designated by K, A, A1, and A2). Moreover, the outer cutter is held so as to be movable up and down in the skin supporting rim, and the outer cutter is also pushed upward with the constant force in which the rotating shaft pushes the inner cutter up.
In general, the upward pushing pressure of the outer cutter influences both the burning sensation remaining in the skin when the hair has been shaven, and the occurrence of deep shaving. The desirable pressure varies greatly depending on personal preference and the condition of the skin and the like, so that it is undesirable to set the pressure at some universal value. Conventionally, however, that pressure (the upward pushing force on the outer cutter) has been set, model by model, at a fixed value, and that has not necessarily always agreed with the preference of the user. For that reason, dissatisfaction has arisen, with that pressure being either too strong or too weak, depending on the user. This has resulted in a limitation on the degree to which shaving comfort could be enhanced.